#include "Comm.h"

class Solution {
public:
    int longestPalindromeSubseq(string s) {
        int n = s.size();

        vector<vector<int>> dp(n, vector<int>(n, -1));

        for (int i = n - 1; i >= 0; --i)
        {
            for (int j = i; j < n; ++j)
            {
                if (i == j) dp[i][j] = 1;
                else if (s[i] == s[j] && i + 1 == j) dp[i][j] = 2;
                else if (s[i] == s[j]) dp[i][j] = dp[i + 1][j - 1] + 2;
                else dp[i][j] = max(dp[i + 1][j], dp[i][j - 1]);
            }
        }

        return dp[0][n - 1];
    }
};